ACPICA: Remove the MTMR (Mid-Timer) table

ACPICA commit 2c39dcccda4dc250a44379ae086b8b1a3fdad115

This table is no longer in use, and is not officially defined
in the ACPI specification.

Link: https://github.com/acpica/acpica/commit/2c39dccc


Signed-off-by: Al Stone <ahs3@ahs3.net>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Erik Kaneda <erik.kaneda@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>